基于阻抗特性的高速列车牵引变流系统谐波谐振稳定性研究

In a high-speed railway, traction power supply and traction converters with different trains form a single-phase AC distributed system, the types of traction converters are two-level or three-level AC/DC/AC topologies. These converters in trains show charateristic of high operating density, fast moving speed and complex working conditions. High-frequency voltage resonant in power supply can cuase DC-link voltage oscillation, which means resonant instability of traction converter and has seriously harm to the stable operation of trains. Considering coupling between output harmonic impedance of traction power supply and input harmonic impedance of traction converters, instability mechanism is analyzed and restraining method of voltage oscillation in traction converters for high-speed train is proposed. Time-domain model of traction power supply – traction converters system is built. Based on wide band signal perturbation, the output harmonic impedance of traction power supply is measured. And input harmonic impedance of traction converters is analyzed considering the impact of characteristic harmonic and parameters tuning of control. Impedance based stability criterion is used to analyze the operating performance of traction converters system. And a multivariable-feedback active-damping method is proposed to restrain the oscillation of traction converters system. At last hardware-in-the-loop simulation is realized to verify the research. This project will reveal the instability mechanism of traction converters system under the resonant impact, also will have important meaning to optimal design and safe operation of traction systems.

高速铁路牵引供电-多列车牵引变流系统是一种单相交流分布式系统，其中牵引变流子系统为AC/DC/AC结构，具有多种拓扑、高运行密度、高速移动和运行条件复杂特点。牵引供电网中存在的谐波谐振会诱发牵引变流系统电压振荡，造成变流控制失稳，严重影响列车安全可靠运行，该问题产生机理尚不明确。项目拟从牵引供电系统输出谐波阻抗和列车牵引变流系统输入谐波阻抗耦合的角度，分析谐振作用下高速列车牵引变流系统失稳机理并提出抑制策略。采用宽带信号注入法研究αβ和dq坐标系下单相牵引供电网输出阻抗特性；考虑特征谐波及牵引控制系统参数影响，研究牵引变流系统输入阻抗特性；基于阻抗耦合稳定性准则研究谐波谐振作用下牵引变流系统失稳机理，提出多变量状态反馈有源阻尼控制方法研究振荡抑制，采用半实物平台验证机理。项目有望全面揭示谐振作用下高速列车牵引变流系统失稳机理，对保障高速铁路牵引供电-变流系统安全稳定和优化设计具有重要意义

随着高速列车行车密度的增加，不同技术参数的高速列车在同一供电线路下运行时车-网间会相互影响，谐波谐振作用下极易诱发车载牵引变流系统失稳现象。基于此，本项目以车-网耦合系统为研究对象，建立了DQ坐标系下的多列车-牵引网系统小信号阻抗模型及牵引网变流器在交流侧端口的谐波导纳矩阵。通过所提的扰动幅值自调节的阻抗测量方法，验证了建模的正确性并分析牵引供电网输出谐波阻抗规律。运用所提的基于禁区的改进型稳定性判据判定了车-网系统低频振荡的临界车辆数，分析了系统各参数对低频振荡现象的影响规律，结合主导极点法，进一步揭示了车-网系统失稳振荡机理。针对失稳现象，提出了三种车载低频振荡抑制策略（非线性PI控制器、自适应自抗扰控制器和线性自抗扰控制器），能够有效地抑制将车-网系统低频振荡发生、提高临界振荡车辆数；在此基础上设计了牵引变流器的优化控制算法，有助于提升变流器的稳态精度和动态响应速度。所提的稳定性判据、车-网阻抗匹配规律及抑制策略和优化算法在基于RT-LAB的车-网系统硬件在环实时仿真平台中得到了测试和验证。项目研究成果对保障高速铁路牵引供电-变流系统安全稳定运营和优化设计具有理论指导和技术推动作用